Wall board



Patented Nov. 13, 1934 UNITED STATES WALL BOARD Arthur Hugo Harrison, Gold Pines, Ontario, Canada No Drawing. Application October 28, 1933, Serial No. 695,667

6 Claims.

This invention relates to wallboard of the character containing a mineral core covered with fibrous liners of paper or the like.

The object of the invention is to provide a board having a core formed from a material which is everywhere plentiful and which may be hardened by the use of waste gas liberated upon its formation, the board being strong and resistant to damage incident to its use and having an intimate self-forming bond between the core and the liners.

In accordance with the invention the core consists essentially of calcium carbonate which is formed in place between paper liners by the action of carbon dioxide on lime, the carbonate during its formation forming a self-sustaining bond between the core and the liners.

In manufacturing the board, lime is mixed with water to form a slurry which, if desired, may be aerated in accordance with the procedure of my prior application for patent, Serial Number 690,340, filed September 21, 1933. The slurry, preferably aerated, is then molded between paper liners to form board of the desired thickness in a manner well known in the art. While supporting the board to avoid rupture of the core it is subjected to carbonation in the presence of carbon dioxide gas to convert the lime to calcium carbonate, which adheres directly to the liners. Part of the slurry water may be removed prior to carbonation or drying and carbonation may proceed simultaneously. It is not necessary that all of the lime be wholly carbonated but carbonation should proceed until at least of the lime has been transformed into the carbonate, which may be calcium carbonate or a mixture of calcium and magnesium carbonate, depending upon the character of the lime used. It is, of course, essential that carbonation be effected in all parts of the board in order to harden the core and provide a bond with the liners. Carbonation is most nearly complete adjacent the edges of the board, which is the weakest part of boards of this general character. Thus this particular board has edges which are well adapted to resist breakage. Ninety percent of the lime may be readily carbonated but for some purposes lesser carbonation is sufficient. A temperature around 180 F. may be used to insure removal of slurry water but substantially higher temperatures may be employed particularly if the carbonating atmosphere is maintained in a humid condition. When carbonation is complete the board may be cut into desired lengths or cutting may be effected at an earlier stage.

When the board is formed from dolomitic lime 90% of which is carbonated, the core'contains substantially 40% of carbon dioxide. The board is strong and hard and has a firm bond between core and liners. When carbonation is 59% complete, the core contains substantially 27% of carbon dioxide. Inasmuch as carbonation is most nearly complete at the edges of the board, the edges are hardest and have the most secure bond between the liners and the core. Thus peeling of the liners does not readily occur even if maximum carbonation is not efiected throughout the core.

When an aerated slurry is used, as will be the case when a light board with maximum insulating capacity is desired, the core will be inter spersed with cells, the walls of which consist essentially of carbonate of calcium or magnesiuri or of both combined when dolomitic lime is use It is permissible to use liners of diiferent character to that ordinarily used in wall board. For example, an ordinary paper liner of the usual character may be used for the under surface and a more porous liner for the other surface.

It will be apparent thatboard of this character is capable of resisting substantial temperatures in that the core will not break down until the applied temperature is such as to cause the carbon dioxide of the carbonate core to be driven off.

I claim:

1. A wallboard having a core of carbonated lime and a fibrous liner on at least one face of said core and bonded thereto by the formation in situ of said carbonated lime.

2. A wall board comprising a core and fibrous liners adhering thereto, said core being filled with cells the walls of which consist of carbonated lime formed Within the core, and said carbonated lime forming the bond between the core and the liners.

3. A wallboard comprising a core containing lime at least 60% of which is carbonated within the core, and paper liners adhering to said core.

4. A wallboard comprising a core and fibrous liners adhering thereto, said core consisting of at least partially carbonated lime, the marginal portions of the core being more highly carbonated than the central portion.

5. A method of making wallboard Which comprises molding a slurry of lime between paper liners and carbonating the lime to harden said core and form a bond between the core and said liners.

6. A method as defined in claim 5, wherein said slurry is aerated before molding.

ARTHUR HUGO HARRISON. 

